As is well known in the art, organopolysiloxanes are generally prepared by hydrolysis and polycondensation of organochlorosilanes or organoalkoxysilanes in the presence of various catalysts. For example, JP-A 2002-226490 describes the synthesis of n-propylethoxysiloxane by subjecting n-propyltriethoxysilane to reaction in ethanol and water in the presence of hydrogen chloride catalyst under reflux conditions. JP 3474007 discloses the synthesis of a polysiloxane by hydrolysis and polycondensation of an alkoxysilane having an organic functional radical in the presence of a neutral fluorinated compound. Many other hydrolytic condensation catalysts have been proposed thus far including acids, bases and metal compounds. The methods using these known catalysts are directed to the production of not only oligomers, but also polymers, despite some monomers left unreacted, rather than selective hydrolysis and polycondensation of monomers into oligomers. Accordingly, there is a need for a method of preparing polysiloxanes with minimized contents of monomers and polymers.
Citation List
Patent Document 1: JP-A 2002-226490 (EP 1205481 A2, Us 20020090316)
Patent Document 2: JP 3474007